The present invention relates to individual equipment for protecting personnel exposed to so-called "NBC" threats (threats of nuclear, bacteriological, or chemical contamination).
In general, such individual equipment comprises a helmet, a complete face-cover fitted with fastenings for fixing to the helmet, and a coupling for a breathing or ventilation gas feed hose, and a flexible envelope, often called a "neck seal", that extends the helmet and the face-cover downwards, together with means for providing a leakproof connection between the helmet, the face-cover, and the envelope. The helmet provides protection against perforation and against shock, and it also serves as a support for various elements such as earphones and a transparent visor.
This structure enables personnel to use only the helmet when performing a mission that does not include an NBC threat. This avoids the discomfort of the elements of items of equipment that completely envelop the face and the neck. However, when personnel is informed prior to a mission that there is a risk of NBC attack, then the envelope is fitted to the helmet. When the presence of an actual threat is indicated, either by sensor means carried by a vehicle occupied by personnel, or else on receipt of a message, the user engages the face-cover and secures it to the helmet, after switching on the ventilation system for supplying filtered air or the system for supplying breathing gas. The first situation arises in particular in helicopters that operate at low altitude and that are consequently not fitted with a source of oxygen under pressure, and it also occurs on military transport that operate at moderate altitude.
To avoid the existence of a "triple" point, where the helmet, the face-cover, and the envelope are interconnected directly, U.S. Pat. No. 5,575,278 (Bonhomme et al.) describes equipment in which the means for providing a leakproof connection between the helmet, the face-cover, and the envelope comprise a monolithic hoop removably connected to the helmet, having a lower branch that constitutes a closed bottom loop for receiving the envelope and a transverse branch constituted on one side to fit to the shell of the helmet and on its opposite side to receive a gasket of the face-cover.
In a particular embodiment described in U.S. Pat. No. 5,575,278, the face-cover includes an upwardly projecting yoke having a transverse pin, while the helmet has a fork designed to receive the pin. The connection by means of a pin and a fork is complemented by lateral fastenings carried by the face-cover and engaged on the helmet.